Colic causes babies to cry uncontrollably for long periods of time.
Researchers studied 36 babies. Half of them had colic.
They say the bacterium causes intestinal inflammation, making the child very uncomfortable, causing it to cry.
The cause of the problem is still a mystery. However, researchers say bottle-fed babies seem to get it more often than breast-fed infants.
The study appears online on the Journal of Pediatrics Web site.
Journal of Pediatrics contributed to this report.